In order to reduce fuel consumption and/or increase power in internal combustion engines, and/or to reduce toxic emissions and noise and/or to enable reliable operation with so-called alternative fuels, an intensive cooling of the cylinder head is necessary. In Diesel engines, the injection valves must be particularly well cooled in order to prevent carbonization of the nozzles. In Otto engines, the spark plugs must be particularly well cooled in order to avoid knocking. In pilot injection Diesel-alcohol engines, the pilot injection nozzle which is cooled very little must be thermally relieved by good cooling. In high-compression, spark-ignited Diesel-alcohol engines, the injection valves and the spark plugs must be cooled particularly intensively in order to assure the reliable operation of both elements. Finally, it is also desirable in Otto-type gaseous fuel (gas) engines to cool the spark plugs intensively.
From German Utility Model DE-GM No. 82 14 976.3, a cylinder head as generally described above is already known, the receptacle socket of which is embodied only for receiving an injection valve. In the vicinity of its end facing the lower cylinder wall, the socket is embodied with a seating face in the form of a male cone, which rests against a matching frustoconical seating face in the manner of an internal or female cone, which is embodied in the corresponding lower cylinder head wall. This assures a highly tight, radially and axially reliable seat for the receptacle socket on the lower cylinder head wall, which also brings about an improvement in cooling as compared with earlier conventional seat embodiments, so that fissures in the material are also reliably prevented. Under particularly severe thermal loads, however, the cooling in this area is still unsatisfactory.